The present invention relates generally to new and novel limited slip motor vehicle differential assemblies. More particularly, the present invention relates to limited slip differential assemblies for motor vehicles which provide a predetermined amount of resistance to slip or differentiation between the differential side gears, the differential pinion gears and/or the axle shafts, and the differential housing to provide some minimum level of torque to each of the motor vehicle wheels at all times.
Motor vehicle differential assemblies have been in common use for many years to allow one motor vehicle wheel on an axle to rotate at a different rate than the other motor vehicle wheel, such as would occur when a motor vehicle is turning, or two tires having different diameters are being used on the same axle. However, to prevent "excessive" slip or differentiation between the motor vehicle wheels, as might occur when one tire encounters a low-traction condition, such as snow or ice, it is desirable for the motor vehicle differential assembly to include some provision to provide some minimum level of torque to each of the two motor vehicle wheels at all times.
Known prior art motor vehicle differential assembly "locking" systems have generally utilized clutch plates or other surfaces which are selectively brought into contact with each other to provide friction. These clutch plates or other surfaces are normally spring loaded and work to prevent differentiation to some degree by providing friction therebetween. Thus, in order for the axles to differentiate, this friction must be overcome. In addition, gear separation forces can act to further load or compress the frictional surfaces so that under high torque conditions, it becomes even more difficult to differentiate. While these types of motor vehicle differential systems will insure that some torque is going to both wheels under any condition, these types of systems can add considerable cost to the differential assembly because of their complexity. Limited slip differential systems are also known which rely on perforated plates that shear through a high viscosity liquid to create drag which must first be overcome before the axles can differentiate. These limited slip differential systems are also relatively expensive due to their complexity. Thus, a more cost-effective, simplified system of providing some minimum level of torque to each of the two motor vehicle wheels in a motor vehicle differential assembly would be desirable.
Preferred embodiments of the present invention are, therefor, directed to limited slip motor vehicle differential assemblies having a suitable high-shear strength, non-hardening, material which selectively resists slip or differentiation between the axle shafts and the differential housing, between the differential side gears and the differential housing, between the differential side gears and the differential pinion gears and/or between the differential pinion gears and the differential housing when slip or differentiation occurs between two motor vehicle wheels mounted on the same axle. Such an arrangement provides some level of torque to each motor vehicle wheel at all times. The amount of resistance to slip or differentiation between the two motor vehicle wheels can be adjusted as desired by selecting an appropriate high-shear strength, non-hardening, material to provide the desired level of resistance to slip or differentiation between the two motor vehicle wheels in the motor vehicle differential assembly.
Accordingly, limited slip motor vehicle differential assemblies in accordance with the present invention provide a simple, cost-effective, arrangement for providing some minimum level of torque to both wheels at all times. This can be particularly beneficial when one of the two motor vehicle wheels on the same axle encounters a low-traction condition, such as snow or ice.
Other advantages and novel features of the present invention will become apparent in the following detailed description of the invention when considered in conjunction with the accompanying drawings.